Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys

Yong Zhang; Z. Guo; Guo Qing  Zhang; Jia Wei Mi; Patrick S. Grant

doi:10.4028/www.scientific.net/MSF.654-656.1363

Paper Titles

Directional Solidification and Characterization of Al₂O₃/Er₃Al₅O₁₂ Eutectic In Situ Composite by Laser Zone Remelting
p.1347

Microstructure Evolution and Compression Properties of a Directionally Solidified Ni-24.8%Nb Hypereutectic Alloy
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The Contribution of Diffusion Coefficient to the Eutectic Instability and Amorphous Phase Formation
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Analysis of an Equiaxed Dendrite Growth Model with Comparisons to In-Situ Results of Equiaxed Dendritic Growth in an Al-Ge Alloy
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Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys
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The Influence of External Mechanical Stresses on Agglomeration and Bending of Solidifying Crystals
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Undercooling Behavior and Solidification Microstructure Evolution of Sn-Cu-Ni Solders Modified by Minute Amount of Mixed Rare Earth La-Ce
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Strength and Conductivity of Deformed Cu-Fe Composites after Solidified with a Horizontal Magnetic Field
p.1377

Solidification Mechanisms in the Sn-Cu-Ni Lead-Free Solder System
p.1381

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Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys

Abstract:

This paper presents a combined experimental and modelling approach to understand dendrite fragmentation of atomised metal alloy droplets during deposition in spray forming, and to study quantitatively the relationship between this dendrite fragmentation behavior and subsequent microstructural evolution. A Gleeble 3500 physical simulator was used to create controlled thermal shock conditions in solid-liquid mixtures of Ni superalloy IN718 atomised powders, which simulated the environment of droplet deposition during the twin-atomiser spray forming of large diameter IN718 alloy billets at BIAM. The experiments were complemented by phase field modelling studies at Oxford. Experiment and modelling supported the hypothesis that the characteristic equiaxed spray formed microstructure depends critically upon the rapid remelting and thermal shock of fine-scale dendrites in solid particles in the spray to provide a high density of embryonic grains.